Social-learning abilities of wild vervet monkeys in a two-step task artificial fruit experiment

Abstract

Keywords artificial fruit Chlorocebus aethiops field experiment local enhancement manipulation task solving social learning tradition vervet monkey Social learning is the basis for the formation of traditions in both human and nonhuman animals. Field observations and experiments provide evidence for the existence of traditions in animals but they do not address the underlying social-learning mechanisms. We used an established laboratory experimental paradigm, the artificial fruit design, to test for copying of a sequence of actions and local enhancement in six groups of wild vervet monkeys, Chlorocebus aethiops. We introduced a two-step task where models had to remove a bar to untie a rope that blocked a single door of a box. The models were high-ranking individuals that monopolized the box early on and discovered by trial and error how to open it. We obtained successful models in three groups, while the other three groups acted as controls. After 20 successful demonstrations, we tested subjects with a box that had a rope in the same position but the rope was not functional. Under these conditions, sequential copying of the two-step opening did not occur. Only individuals that were exposed to models were likely to touch the bar if door opening was not immediately successful, providing evidence for local enhancement. When we presented the boxes with the functional rope, we found no effect of having been exposed to a model on the probability that subjects solved the task. We conclude that the social-learning abilities of wild vervet monkeys are relatively limited and discuss potential problems concerning the technical difficulty of the task.

On the neglected behavioural variation among neighbouring primate groups

“…Studies of multiple groups of wild primates within single populations have demonstrated social learning through field experiments (in four groups of lemurs, Schnoell & Fichtel, ; in up to 13 groups of marmosets, Gunhold, Massen, Schiel, Souto, & Bugnyar, ; Gunhold Whiten, & Bugnyar, ; in up to six groups of vervet monkeys, van de Waal et al, ; van de Waal et al, ; van de Waal, Borgeaud, et al, ; de Waal et al, ; de Waal, Claidière, & Whiten, ; van de Waal & Bshary, ). However, long‐term observations of these populations, with the aim of revealing potential intergroup differences, are to my knowledge lacking, until this present review of behavioural variation in wild vervet monkeys.…”

“…The study was conducted from July 2007 This site was chosen for the presence of a tourist road passing through the territories of six groups of vervet monkeys (Chlorocebus pygerythrus) allowing observers to travel easily from one group to another. The six groups were subject to social learning experiments during the course of this study (van de Waal & Bshary, 2011;van de Waal et al, 2010;van de Waal, Krützen, Hula, Goudet, & Bshary, 2012). All group compositions are detailed in Table 2.…”

Social Information Transmission in Animals: Lessons from Studies of Diffusion

“…In a two-step foraging task, vervet monkeys ( Cercocebus aethiops ) had to remove a rope blocking a door before opening that door to retrieve food. Although the trained model was ultimately successful at the task, other individuals failed to master it although they were exposed to a successful model, suggesting that the link between one gesture and the next in a several-steps task was not evident ( van de Waal and Bshary, 2011 ). Another example of a behavior, this time naturally occurring, that failed to spread is dental flossing in Japanese macaques ( Leca et al, 2010 ).…”

Resilience of experimentally seeded dietary traditions in wild vervets: Evidence from group fissions

“…Such evidence is often strongest in laboratory or other captive contexts where experimental controls are most tractable to arrange, most importantly the provision of opportunities to learn from a model performing a novel action, contrasted with a no‐model control condition, and/or to learn from either of two models displaying different behaviors. However, in the service of better understanding the implications of such social learning in the natural lives of animals, a small but growing number of experiments following these and other designs have now been engineered in the more challenging circumstances of the wild, providing evidence of social learning in a range of primates (Gunhold, Massen, Schiel, Souto, & Bugnyar, ; Gunhold, Whiten, & Bugnyar, ; Kendal et al, ; Schnoell & Fichtel, ; Schnoell, Dittmann, & Fichtel, ; van de Waal & Bshary, ; van de Waal, Borgeaud & Whiten, ; van de Waal, Renevey, Favre, & Bshary, ) and other mammalian and avian species (Aplin et al, ; Slagsvold & Wiebe, ; Thornton & Clutton‐Brock, ). Additionally, new statistical techniques like social network diffusion analyses have offered complementary and compelling evidence for social learning in wild birds (Aplin et al, ), primates (Hobaiter, Poisot, Zuberbühler, Hoppitt, & Gruber, ) and cetaceans (Allen, Weinrich, Hoppitt, & Rendell, ).…”